import math

x1,y1,x2,y2,x3,y3 = eval(input('Enter three points for a triangle: '))
side1 = math.sqrt(pow(x1 - x2,2)+pow(y1 - y2,2))
side2 = math.sqrt(pow(x1 - x3,2)+pow(y1 - y3,2))
side3 = math.sqrt(pow(x2 - x3,2)+pow(y2 - y3,2))
s = (side1 + side2 + side3) / 2
area = math.sqrt(s * (s - side1) * (s - side2) * (s - side3))
print('The area of the triangle is ' + format(area,'.1f'))